Fuel cells have recently been highlighted as cells that exhibit a high level of efficiency and excellent environmental characteristics. In a fuel cell, generally, the oxygen within air, which functions as an oxidant gas, is subjected to an electrochemical reaction with hydrogen, which functions as a fuel gas, thereby generating electrical energy. As a result of the electrochemical reaction between the hydrogen and oxygen, water is generated.
Varieties of fuel cell include phosphoric acid fuel cells, molten carbonate fuel cells, solid electrolyte fuel cells, alkali fuel cells and solid polymer fuel cells. Of these, solid polymer fuel cells, which offer certain advantages such as ambient temperature startup and a rapid startup time, are attracting particular attention. This type of solid polymer fuel cell can be used as the power source for moving objects such as vehicles.
A solid polymer fuel cell is assembled by laminating a plurality of unit cells, a current collector and an end plate and the like. Each cell for the fuel cell comprises an electrolyte membrane, a catalyst layer, a gas diffusion layer and a separator.
Patent Document 1 discloses a method of using gold plating to impart stainless steel with excellent soldering properties and wire bonding properties at low cost, wherein as a pretreatment, the surface of the stainless steel is highly activated by subjecting the stainless steel to cathodic electrolysis in two separate stages in electrolysis baths comprising an inorganic acid and an organic acid, so that when gold plating is performed, pinholes and the like do not occur, and the plating adhesion improves markedly.
Patent Document 2 discloses a metal separator for a fuel cell in which a portion of the stainless steel is plated with the premise of avoiding significant increases in the manufacturing cost, wherein the separator yields excellent contact resistance with the gas diffusion electrode and has excellent corrosion resistance that enables the lifespan required of a separator to be achieved, and wherein a conductive inclusion is exposed through the surface having corrosion resistance, and the region of the surface where the conductive inclusion is not exposed is coated with gold.
Patent Document 1: JP 61-243193 A
Patent Document 2: JP 2004-71321 A